EP 0 960 024 discloses a method for producing partially embossed cover elements of a film material for sealing containers. The film material contains pre-dimensioned cover elements and is guided between two embossing rollers. The spacing between the cover elements is readable by means of a sensor via pressure marks. A second sensor in an angle position supplies additional values. The values are compared and transmitted to the motor to control the speed of the supply device.
U.S. Pat. No. 8,459,087 discloses a method for producing blanks, the blanks having an embossed surface and being stamped from a continuous material. On the continuous material markings are stamped when the surface of the blank is embossed, said markings being used for the position determination during stamping process.
The blanks disclosed in the instant application are understood as being blanks for covering containers, for example containers in form of cups or trays. Such blanks are widely used as covers for covering cups and trays in the food industry and in the pharmaceutical industry. In particular, the blanks form covers or lids for cups and trays for dairy products etc. Accordingly, the web for the blanks consists of an embossable material. Using the blanks for example as cover or lids in an automated packaging process an embossed pattern is essential to allow an easy separation of the single blanks in an automated process. The embossing of the blanks is not only essential to achieve easily processable blanks, e.g. as mentioned above in terms of de-stacking blanks that are stored in stacks before they are processed further. The embossing additionally provides the possibility to create specific designs on the blanks, e.g. figures or a product name. However, if there are specific designs embossed on the blanks, it becomes desirable that the design has a fixed position on the blank which does not shift in the manufacturing process of the blanks eventually resulting in a mutilated design due to punching of the blank from the web. Thus, the blanks need to be die cut at a defined position in register with the embossing.
The precise positioning of the embossing in connection with the exact die cutting of the embossed blank from continuous web is still difficult to achieve.